This invention relates to a curable resin composition comprising a mixture and/or a preliminary reaction product of (a) a polyfunctional cyanate ester, prepolymer of the cyanate ester or coprepolymer of the cyanate ester and an amine (sometimes hereinunder referred to as component (a)) and (b) polyhydantoin resin (sometimes hereinunder referred to as component (b)) and also relates to a curable resin composition comprising a mixture and/or a preliminary reaction product of component (a), component (b) and (c) a polyfunctional maleimide, prepolymer of the maleimide or coprepolymer of the maleimide and an amine (sometimes hereinunder referred to as component (c)).
Polyhydantoin resins have good water resistance, and are commercially available as an enamel varnish or in the form of film. However, solvent-resistance of the resin is slightly poor and heat-resistance thereof is somewhat unsatisfactory. In addition, it is not suitable to make laminate from the resin. On the other hand, cyanate ester resins are slightly poor in respect of water-resistance. Cyanate ester-maleimide resins were developed in order to improve the above shortcoming of the cyanate ester resin. Flex resistance of the cyanate ester-maleimide resin is too low for the resin to be used as an enamel.